Over the years I have worked with a number of people that had confusing results with arrow spines. i have seen guys come up with some wild things. for myself when I am going to make arrows for someone else, it is more difficult to predict when there is a lot of extra shaft. That extra long arrow will react differently for different bows and different people, although it is possible to find a sweet spot, it is difficult to declare it without experimenting. I have also seen that often arrow flight flight confusions start with a variable release. An over spined arrow, over length and with an extra heavy point can seem like the perfect answer for someone with a feathered weak release with a high nocking point. Then down the road the release improves and everything goes wrong, the last thing they think of is that the release just got more balanced and stronger, or if it started out strong, it perhaps got weaker. While everyone always looks for the mechanical variant, the human variant is at fault more often than not. i caught myself having some arrow flight variations recently, a variety of things, one time a porpose, next time a a half arc tail whip. the problem was not a nocking point height, a brace height, or a draw length variation. It was my release fingers and some off line muscle tension. I went from wacky arrow flight to perfect arrow flight and I did not change a thing, except me.